This invention pertains to a valve assembly with decompression means and, more particularly, to a solenoid-operated valve assembly that will direct pressure fluid to a control port connectable to a cylinder or the like and hold pressure at the cylinder when flow to the inlet port is stopped. When the solenoid is energized the pressure of the fluid is reduced slowly from high pressure to low pressure, with this being accomplished by decompression means and, thereafter, the valve assembly is opened fully to allow free flow from the cylinder to the control port and from there to a return port leading to a reservoir. Additionally, a leverage system is used to achieve the necessary force for enabling operation of the valve assembly by a solenoid.
Control valves for controlling the flow to a cylinder and for holding pressure in the cylinder are known. For example, such a structure is shown in Solie U.S. Pat. No. 3,934,610. The valve disclosed in the Solie patent includes means for reducing the pressure held in the cylinder prior to complete opening of the flow path from a control port to the return port. The Solie patent discloses operation of the decompression means and valve structure either by hydraulically-powered pilot members or by a hand lever.
The Mott U.S. Pat. No. 2,381,553 discloses a control valve with two different valve members operable in sequence determined by the stroke of an operating member for first reducing a pressure and then opening a main flow path to a return port.
The above prior art does not disclose a valve assembly having a force-multiplying leverage system enabling operation of valve components directly by a solenoid nor does the prior art show a system wherein opening of a main valve to permit flow from a control port to a return port is directly responsive to the value of the reduced pressure within the valve.
It is also known in the art to use a pair of interacting levers to open a valve in response to operation of a solenoid.